Hey all,
I've been experiencing for the last 6 months (probably more like a year) issues with starting the car after a run on a hot day - in Australia, there are usually at least 300 of these days in a year.

Some of you have experienced this symptom and have simply replaced the starter motor - at which point you have probably cleaned up some wiring and eliminated your issue anyway.

I opted for the ford remote solenoid, as they are generally unkillable, after installing the solenoid, i bumped up the gauge of wiring, redid the terminals on the secondary side only, the primary was simply cleaned and reattached. The difference was night and day, i could drive for hours and simply turn the key and continue on. Until we hit a 45 Degree (113F) day, and the problem came back. Turn the key... nothing.

Thanks to the Ford solenoid, starting was as simple as getting out a screwdriver and bridging the terminals - away i went, however this was still irritating me...

I decided that there must be something wrong with the primary wiring (Key > Solenoid) so i traced the wire all the way back, found nothing - 2 days later, 44C day and it happened again. i had a test light so i quickly threw it onto the primary wire and there was zero voltage. When i got home i traced the wire again and when i grabbed part of the wire (about 1 inch long) it made a crunch sound. Figuring i was going to replace it anyway, i cut into that patch and found crystalized copper. This piece of wire was not near a heat source or anything, so what caused this wire to fry is still a bit of a mystery. Though being 30 odd years old i really didn't care that much and replaced it. since then the issue has disappeared entirely.

Parts and cost were about $25 for the wiring, terminals and the solenoid. To get another starter motor here would have been into the $150 mark and still not have solved my issue due to the wiring. I'm calling it a win.